Abstract

Water quality of a region directly corroborates with the health index of people. People in the Himalayan hills mainly depend upon the spring water for potability. To determine the microbial ecology of the spring waters of Sikkim, the variable region of 16S rRNA has been sequenced using Illumina MiSeq. Phylum wise annotation showed the East and North district are mostly dominated by Proteobacteria (41% and 35.80%), whereas West and South district is dominated by Planctomycetes (38.46%) and Verrucomicrobia (33%). The consistent dominance phyla in the all the four districts were Bacteriodetes (34–24%) which was highest dominancy in North district and lowest in wets district. Genus wise distribution showed the abundance of Brevifolis, Flavobacterium, Verrucomicrobia subdivision3, Emticica, Cytophaga, Prosthecobacter, Planctomycetes, Varivorax, Arcicella, Isosphera, Sedimunibacterium etc. The East district showed highest dominancy of genus Emticicia whereas Planctomycetes in the West district. The North district was mainly dominated by genus Arcicella and Brevifollis in the South district. North on the antonymous showed totally different sets of microbial diversity. North district showed an abundance of Arcicella, Planctomycetes, Schlerensia and Azohydromonas. The heat map produced by Bray Curtis distance method produced three clusters which showed the close relationship between West and East district microbiome that further related to South district. The sample of North district formed out group that showed different community structure from other three districts. The principle component analysis was showed that the east and South district samples are closely related and distantly correlated to the west Sikkim, but the North district showed completely different microbial community. The canonical correspondence analysis showed correlation between bacterial diversity and hydrochemistry and it was found that the bacterial diversity was influenced by the concentration of different metallic ions like sodium, calcium, barium and iron. This is a first report from the Eastern Himalayan region of India and it largely enhances our knowledge about the microbial structure of potable spring water of Eastern Himalayan. This study is useful for Government of India as well as the state government to adopt the different strategic treatment procedures to improve the quality of water that is supplied to the community resides in the Himalayan regions and solely dependent on this untreated spring water.